I'm keeping my eye on Chaos Vantage for exactly what you're talking about. It's currently only serving up VRAY, but Corona is supposed to get support and accessibility in it's next release. So I'm hoping this is somewhere between Cinema and Unreal for client walkthroughs and quick animations. I know about Twinmotion, but the appeal of Vantage is not having to do any alterations to your normal Cinema scene in regards to lighting, materials and Cameras. Just waiting for that. I love Unreal, but it's a haul to get full scenes or interiors going properly.